Switch for electric circuits



I. DEUTSCH.

SWITCH FOR ELECTRIC CIRCUITS. APPLICATION HLED 111111.23, 191i. RENEWEDNOV. 19, 1919.

1,339,922, Emma May11,1920.

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WITNESSES! Z 9 INVENTQE I 9 BY 2 ATITORNEY I. DEUTSCH.

SWITCH FOR ELECTRIC C IRCUITS. APPLICATION FILED MAR. 23, 1911. RENEWEDNOV. 19,1919.

1,339,922. Patented May 11, 1920.

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UNITED STATE PATENT ISIDOR DEUTSCH, 0F AVALON, PENNSYLVANIA, ESSIGNQR T0'WESTINGI-IOUSE ELEC- TRIO AND MANUFACTURING COMPANY, A GOBPORATISN OFPENNSYLVANIA.

SWITCH FOR ELECTRIC CIRCUITS.

Specification of Letters Patent.

Application filed March 23, 1911, Serial No. 616,474. Renewed November19, 1919. Serial No. 339,065.

To all whom it may concern:

Be it known that I, Ismon Dnu'rsor-r, a citizen of the United States,and a resident of Avalon, in the county of Allegheny and State ofPennsylvania, have invented a new and useful Improvement in Switches forElectric Circuits, of which the following a specification.

My invention relates to switches and sys tems for the control ofelectric circuits and motors, and it has for its object to provide asimple and particularly advantageous switching device for use inconnection with motor control systems of the unit switch type.

Unit-switch control systems, which have been very largely used, comprisea plurality of independently operated switches designed and connected toact successively to govern the acceleration of electric motors. In thesesystems some independent means are ordinarily employed for delaying theaction of the successive switches in order to avoid injuring the motorby excessive current.

According to my present invention, 1 provide an electric switch havingthe characteristic of occupying its open position, not only when itsactuating magnet is de'e'nergized, but also when energized above apredetermined value. In other words, the switch is closed only whenenergized between predetermined limits. By utilizing a plurality ofswitches of this character in a simple, unit-switch control system, theacceleration of the motor may be advantageously accomplished and the ation of each switch will be delayed until the current traversing themotor circuit has sufliciently decreased to fall within the limits whichdetermine the action of the switches.

In addition to the above-named characteristic, the switch, when closed,will remain closed until its actuating magnet winding is denergized.

Figures 1 and 2 of the accompanying drawings are, respectively, a sideand a front elevation of a switch constructed in accordance with myinvention, the actuating coil being shown in section in Fig. 1. Fig. 3is a diagrammatic view of a control system to which the switch of Figs.1 and 2 is applicable, and Figs. 4 and 5 are views, corresponding toFigs. 1 and 2, of a slightly modified structure which is speciallyadapted for use with alternating current cirouits.

Referring to Figs. 1 and 2 of the drawings, the switch here showncomprises a stationary contact member 1, a movable contact member 2, astationary core member 3 and a movable core member 4 to which thecontact member 2 is pivotally secured. The stationary core member 3 isof substantially shape, having three legs 5, 6 and 7, the leg 7 of whichis adjustable. On the intermediate leg 6, a coil 8 is mounted, and themovable core member 4 is pivotally secured to its outer end. The coreleg 5 and the movable core member 4 are, respectively, provided withpole pieces 9 and 10 which are in engagement when the switch is closed.The end of the movable core member 4 that is adjacent to the leg 7 isprovided with a set screw 11, or some other suitable means for finingthe air gap between the two members when the switch is open, the member4 being so formed that there is a material air gap either at one of itsends or at the other. A compression spring 12 is interposed between aprojection 13 of the contact-bearing member 14 and a bracket 15 upon theouter surface of the member 4 in order to effect a rotative movement ofthe contact-bearing member upon its pivot 16 ano thus produce a wipingation between the contact members when the switch is opened. Therotative movement of the contact-bearing member is limited by aprojection 17 in order to hold the spring 12 in position and to permitthe contact members to be properly separated when the switch is opened.

The adjustment of the leg plished by screw-threading its engage a tappedhole in the base of the member 3, as shown in Fig. 1, and its positionmay be fixed against accidental displacement by means of a clamping bolt18 or otherwise. The lower end of the member 8 is provided with a slot19 which extends into the tapped hole so that the clamping bolt, whentightened as shown in Fig. 2, locks the leg 7 in position.

The operation of the switch is as follows:

Assuming that the coil 8 is deenergized and that the switch is open, thelower end of the member 4 being separated from the 7 is accominner endto core leg 7 only by means of the set screw 11;

if, under these conditions, a large current is supplied to the coil 8, alarge amount of flux will traverse the magnetic circuit constituted bythe upper half of the core memher and including the core legs 5 and 6.Another magnetic circuit will be established through the lower half ofthe core member including the core legs 6 and 7. The pole pieces 9 and10 and the air gaps are so proportioned that, under the conditionsoutlined above, the core leg 5 will be saturated so that a suflicientflux will traverse the leg 7 to hold the switch open regardless of thepole pieces 9 and 10.

As soon as the current traversing the coil 8 falls below a predeterminedvalue, the pull exerted between the core leg 7 and the movable coremember 4 will decrease very rapidly so that the pull at the opposite endwill predominate and the switch will be closed. If the current firstapplied to the coil is below a predetermined value, the switch will beclosed on account of the size of the pole pieces 9 and 10.

Referring to Fig. 3 of the drawings, the control system here showncomprises line conductors 20 and 21, a line switch 23, resistancesections 241, 25 and 26, accelerating switches 27, 28 and 29 and amaster switch 30. Assuming that each of the switches 27, 28 and 29 hasthe same operating characteristics as the switch shown in Figs. 1 and 2,if the master switch 30 is closed, current will be supplied to magnet 31of the line switch 23, causing this switch to close the circuit toconnect the motor 22 in series with the resistance sections. The motorcircuit is from conductor 21, through the motor, conductor 32, lineswitch 23, magnet winding of the switch 27, resistance sections 24, 25and 26 and conductor 34 to line conductor 20.

In accordance with well known principles, a rush of current will firsttraverse the motor circuit and the switch 27 is so designed as to remainin its open position until the motor has accelerated somewhat and thecurrent has fallen below a predetermined value. It will then close andshort circuit resistance section 24, thus completing the motor circuitfrom the line switch, through coil 33, the switch 27 and coil 35 ofswitch 28 to an intermediate point 36 in the resistance, from whichcircuit is completed as before. The action of the switch 28 is similarto that of the switch 27 and, when closed, short-circuits the resistancesection 25 and supplies energy to the coil 37 of the switch 29.

The advantages of my electric switch will be immediately apparent tothose skilled in the art and, consequently, they will only be brieflyreferred to as follows:

No series relay or other independent means for delaying the action ofthe switches is required: no auxiliary contacts are necessary for thepurpose of interlocking the switches: each of the switches may beidentical in construction and at the same time the limits within whichthe switch will be closed may be adjusted by varying the air gap betweenthe members 7 and 4 when the switch is open. This is accomplished asshown in Fig. 1, by adjusting the setting of the screw 11.

Referring to Figs. 4 and 5 of the drawings, in which corresponding partsare designated by the same reference characters, the coil 8 of Fig. 1 isreplaced by coils 38 and 39, respectively located on the core legs 5 and7, and the structure of the core member itself is laminated for thepurpose of adapting it to alternating current circuits. The core leg 7forms a butt joint with the body of the core and brackets 10 areattached to the body by means of bolts 41. The arrangement of parts issuch that when the lower ends of the brackets 10 are bolted together theposition of the core leg 7 is fixed.

Variations in the size and arrangement of parts of the switch may beeffected within the spirit and scope of my invention and it is capableof very wide application, the sys tem of Fig. 3 being intended merely toillustrate its utility.

I claim as my invention:

1. An electro-magnet comprising a substantially E-shaped core member, arelatively movable core member pivotally secured to the intermediatecore leg of the E-shaped member and an actuating coil, a relativemovement of the core members being effected only when the currenttraversing the coil falls within predetermined limits, one of the legsof said E-shaped member and said relatively movable member havingenlarged pole pieces.

2. An electro-magnet comprising a substantially E-shaped core memberhaving one of its core legs adjustable, and a relatively movable coremember pivotally secured to the intermediate core leg of the E-shapedmember and an actuating coil, a relative movement of the core membersbeing effected only when the current traversing the coil falls withinpredetermined limits.

3. An electro-magnet comprising a substantially E-shaped core memberhaving one of its core legs adjustable, and a relatively movable coremember pivotally secured to the intermediate core leg of the E-shapedmember, a coil, and adjustable means for fixing the minimum air gapbetween the movable core member and the adjustable leg of the E-shapedmember, a relative movement of the core members being effected only whenthe current traversing the coil falls within predetermined limits.

at. An electromagnet comprising a switchcarrying member pivotedintermedlate 1ts ends, two magnetizable members respectively adjacent tosaid ends, one of said magnetizable members being larger than the other,and means for creating two magnetic circuits to respectively includesaid magnetizable members.

5. A controlling device for electric circuits comprising anelectromagnet having two core members, a pivoted switch member having anarmature portion cooperating with each of said core members and normally.in open position, with one armature portion resting adjacent to thefree end of one core member but separated therefrom by an air gap, oneof said core members being of smaller cross-sectional area than theother, whereby it becomes saturated to cause the flux of the magnet tocross the gap through the larger core member and thereby hold the switchopen when the current is high but so reduces the flux across said gap,when the current falls to a predetermined value, that the switch may beclosed by the flux acting upon the other armature portion.

6. In a switch, a magnetic circuit including a stationary mechanism, amovable mechanism and a winding associated with said stationarymechanism for producing magnetic pulls on said movable mechanism at twoplaces, said circuit including also a gap for causing the pulls to varydifferently at said two places when the ampere turns in said winding arevaried, and means for adj usting both o1 said mechanisms to vary saidgap and thereby vary the relation between said pulls 7. An electromagnetcomprising a base having a screw-threaded opening and a slot leadingtherefrom, a screw-threaded core member adjustably mounted in saidopening and a bolt for restricting the area of said slot to clamp saidcore member in adjusted position.

8. An electromagnet comprising a base having an opening and a slotleading there from, a core member adjustably mounted in said opening andmeans for drawing the walls of said slot toward each other to clamp saidcore member in adjusted position.

9. An electromagnet comprising a movable switch member pivoted at apoint intermediate .its ends, two magnetizable members respectivelyadacent to said ends, and means for energizing two magnetic circuits ofdifi'erent reluctances, said circuits respectively including saidmagnetizable members.-

10. An electromagnet comprising a movable switch member, twomagnetizable members respectively adjacent to coacting portions of saidmovable member, and means for energizing two magnetic circuits,respectively including said magnetizable members, to such degrees thatonly one of said magnetizable members is saturated.

11. An electromagnet comprising a member having a pivotal supportintermediate its ends, two magnetizable members respectively adjacent tosaid ends, one of said members being of greater magnetic reluctance thanthe other, and means for energizing two magnetic circuits respectivelyincluding said magnetizable members.

12. An electromagnet comprising a member having a pivotal supportintermediate its ends. two magnetizable members respectively adjacent tosaid ends, one of said members being of greater cross-section than theother, and means for energizing two magnetic circuits respectivelyincluding said magnetizable members.

In testimony whereof, I have hereunto subscribed my name this 14th dayof March, 1911.

ISIDOR DEUTSCH. Witnesses W. BARNES, (In, B. B. HINns.

